The present invention relates generally to interface devices for allowing humans to interface with computer systems, and more particularly to computer interface devices that allow the user to provide input to computer systems and allow computer systems to provide haptic feedback to the user.
A user can interact with an environment displayed by a computer to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), etc. Common human-computer interface devices used for such interaction include a mouse, joystick, trackball, steering wheel, stylus, tablet, pressure-sensitive sphere, or the like, that is connected to the computer system controlling the displayed environment. Typically, the computer updates the environment in response to the user""s manipulation of a physical manipulandum such as a joystick handle or mouse, and provides visual and audio feedback to the user utilizing the display screen and audio speakers. The computer senses the user""s manipulation of the user object through sensors provided on the interface device that send locative signals to the computer. For example, the computer displays a cursor or other graphical object in a graphical environment, where the location of the cursor is responsive to the motion of the user object.
In some interface devices, force feedback or tactile feedback is also provided to the user, more generally known herein as xe2x80x9chaptic feedback.xe2x80x9d These types of interface devices can provide physical sensations which are felt by the user manipulating a user manipulandum of the interface device. One or more motors or other actuators are coupled to the joystick or mouse and are connected to the controlling computer system. The computer system controls forces on the joystick or mouse in conjunction and coordinated with displayed events and interactions by sending control signals or commands to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the interface device or manipulatable object of the interface device. For example, when the user moves the manipulatable object and causes a displayed cursor to interact with a different displayed graphical object, the computer can issue a command that causes the actuator to output a force on the physical object, conveying a feel sensation to the user.
One problem with current force feedback controllers in the home consumer market is the high manufacturing cost of such devices, which makes the devices expensive for the consumer. A large part of this manufacturing expense is due to the inclusion of multiple actuators and corresponding control electronics in the force feedback device. In addition, high quality mechanical and force transmission components such as linkages and bearings must be provided to accurately transmit forces from the actuators to the user manipulandum and to allow accurate sensing of the motion of the user object. These components are complex and require greater precision in their manufacture than many of the other components in an interface device, and thus further add to the cost of the device. A need therefore exists for a haptic device that is lower in cost to manufacture yet offers the user haptic feedback to enhance the interaction with computer applications.
The present invention is directed to a low-cost haptic feedback trackball device connected to a computer system, the trackball device having a simple actuator for low cost force feedback for enhancing interactions and manipulations in a displayed graphical environment.
More specifically, the present invention relates to a haptic feedback trackball device that is coupled to a host computer which implements a host application program. The device includes a housing that is physically contacted by said user, the housing resting on a support surface. A sphere is positioned in the housing, the sphere being rotatable in two rotary degrees of freedom. A sensor device detects the movement of the sphere in the rotary degrees of freedom and outputs sensor signals representative of the movement. An actuator applies a force to the housing approximately along an axis that is substantially perpendicular to the support surface, where the force is transmitted to the user contacting the housing. The force is preferably correlated with a graphical representation displayed by the host computer, where a position of the sphere in the rotary degrees of freedom corresponds with a position of a cursor displayed in the graphical representation.
Preferably, at least one compliant element is provided between a portion of the housing contacted by the user and the support surface, where the compliant element amplifies the force output from the actuator by allowing the contacted portion of the housing to move with respect to the support surface. For example, the compliant element can be one or more feet provided on the underside of the housing and made of a compliant material such as rubber or foam. Or, the compliant element can be a compliant coupling provided between the contacted portion of the housing and a non-contacted portion of the housing.
In some embodiments, the force is an inertial force that is output approximately along the axis that is substantially perpendicular to the support surface, where the actuator outputs the inertial force to the housing by moving an inertial mass. The actuator can be coupled to a flexure that provides a centering spring bias to the inertial mass. The inertial force can be a pulse, vibration or texture correlated with the interaction of a user-controlled cursor with a graphical object displayed in a graphical user interface. For example, the pulse can be output when the cursor moves between menu items in a displayed graphical menu. In other embodiments, the force is a contact force that is provided by driving a moving element that contacts the user. The moving element can be a cover portion of the housing that is movably coupled to a base portion of the housing. Alternatively, the moving element can be a button that also provides button input to the host computer. Some embodiments may include a second actuator, such as a passive brake, for outputting a force on the sphere in its degrees of freedom. A method for providing haptic feedback similarly includes detecting the motion of a sphere of the trackball device, receiving information from the host computer indicating that a tactile sensation is to be output, and outputting a force on the housing of the trackball device approximately along an axis perpendicular to a support surface.
The present invention advantageously provides a haptic feedback, trackball device that is significantly lower in cost than other types of haptic feedback devices and is thus quite suitable for home consumer applications. A single actuator can be provided that applies a force in a particular degree of freedom, such as the Z-axis perpendicular to the support surface, and compliance is provided between surface and user contact. This allows more compelling forces to be experienced by the user, and also enhances the user""s experience of a third dimension relative to the surface plane. Furthermore, the actuator of the present invention can provide a variety of different types of force sensations to enhance the user""s interfacing and experience with a computer application.